Conventionally, electronic devices using a transparent conductive circuit substrate furnished with a wiring portion made of a transparent conductive film including conductive polymers are in wide use (see, for example, Japanese Unexamined Patent Application, First Publication No. 2002-222056).
The above-mentioned wiring portion is typically formed by printing a paste in which conductive polymers are dispersed in water onto a substrate by screen printing or ink jet printing such that the paste is printed in a predetermined shape (for example, in a linear shape).
However, when the wiring portion is formed by use of conductive polymers, the result is sometimes a wiring portion with an imperfect shape. This is because the wiring portion may be deformed by a mixture of bubbles into the paste, by an oozing of the paste on the substrate, or a repulsion of the paste by the substrate, due to properties (viscosity, etc.) of the paste.
When the wiring portion has an imperfect shape, the electrical resistance value of the wiring portion sometimes becomes unstable.
It is possible to adjust the shape of the wiring portion by stackingly coating an additional paste on top of the coated paste. In this case, however, the wiring portion becomes thick, thereby reducing its transparency. Moreover, this has posed a problem that it is disadvantageous in terms of cost because more manufacturing steps are required.